The use of balls to control fluid flow in a subterranean well is well known. The balls are generally dropped or injected into a fluid stream being pumped into the well. This can be accomplished manually, but the manual process is time consuming and requires that workmen be in close proximity to highly pressurized fluid lines, which is a safety hazard. Consequently, ball droppers or injectors have been invented to permit faster and safer operation.
As is well understood in the art, multi-stage well stimulation operations often require that balls of different diameters be sequentially injected into the well in a predetermined size order that is graduated from a smallest ball to a largest ball. While ball injectors are available that can inject single balls in any order, such injectors require that a plurality of injector spools be vertically stacked to achieve the required availability of balls of different diameters. The stacking of injector spools increases weight on the wellhead and raises working height, both of which are undesirable.
There therefore exists a need for a low profile, high capacity ball injector for use during well completion, re-completion or workover operations.